<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <style>
        
        .box {
            position: absolute;
            width: 200px;
            height: 200px;
            background-color: red;
        }
        
        .composited {
            transform: translateZ(1px);
        }
        
        .negative {
            z-index: -1;
        }

        .positive {
            z-index: 1;
            background-color: green;
        }
    </style>
    
    <script>
        if (window.testRunner)
            testRunner.waitUntilDone();

        window.addEventListener('load', () => {
            requestAnimationFrame(() => {
                document.getElementById('target').classList.add('negative');
                if (window.testRunner)
                    testRunner.notifyDone();
            });
        }, false);
    </script>
</head>
<body>
    <p>You should see a green box below.</p>
    <div class="composited box">
        <div id="target" class="box"></div>
        <div class="positive box"></div>
    </div>
</body>
</html>